Dioxins in bile in relation to those in the human liver and blood

The levels of 20 dioxin congeners, 7 polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs) and three coplanar polychlorinated biphenyls (Co-PCBs), in bile were examined in comparison with those in the blood and liver, in 27 autopsy cases. Total-TEQ values were the same in the bile (43.2 ± 30.9 pg TEQ/g lipid) and blood (43.1 ± 24.2 pg TEQ/g lipid), and three times higher in the liver (127.8 ± 57.4 pg TEQ/g lipid). Highly chlorinated PCDDs and PCDFs have a tendency to accumulate in the liver, and their levels in bile and blood were relatively low compared with those in the liver, with 1,2,3,4,6,7,8-heptachlorodibenzofuran having the highest tendency among the 20 congeners. Daily excretion in bile was calculated to be 54 pg TEQ at age 65, by assuming that daily bile secretion is 750 ml and is concentrated 7.5-fold in the gallbladder. The correlation between bile and blood total-TEQ was high, with a correlation coefficient of 0.89 among the 27 autopsy cases. Thus, the regression equation of y = 1.14x - 6.02 will provide us levels in bile (total TEQ per g lipid), knowing the blood total-TEQ level, where x is total-TEQ per g lipid of the blood. Furthermore, accumulation of dioxins was estimated to be 0.99, 0.70 and 1.91 pg TEQ/g lipid/year in bile, blood and liver, respectively.